The primary aim of the proposed research is to investigate psychoendocrine relationships which underlie the adaptation to stress. The studies will evaluate factors which influence the individual's response to stress, with a particular emphasis on experiential variables and social relationships. The pituitary-adrenal and pituitary-gonadal responses of the squirrel monkey (Saimiri sciureus) will be assessed in a wide variety of stressful situations. A time course of the endocrine responses to physiological and psychological stressors will be compared. The effect of sex differences and social status on these hormonal changes will also be determined. In addition, this research will focus on the manner in which social relationships modify stress responses. The areas we propose to investigate include: the attachment relationship between mother and infant, the social relationship between two familiar adults, and the social bond between an individual and its group. Mother-infant studies will be conducted on: (1) the effect of multiple separations at different developmental stages, (2) the effect of sustained separations, (3) the influence of the environment on the separation response, and (4) the influence of familiar adults on the separation response. The infants produced from these experiments will then be studied to determine the role of experiential factors on subsequent responses to stress. Infants from different rearing environments will be compared on a series of behavioral tests that will have been generated from experiments on adult animals. These studies will utilize novel and aversive situations, as well as appetitive and avoidance conditioning paradigms; and assess the role of factors, such as control, predictability, and feedback on the individual's ability to cope with stress. A combination of behavioral observations and hormonal analyses will be employed in these studies. By examining the endocrine response to environmental perturbations (psychological stress) and the modification of the stress response by social stimuli, a better understanding of how a social organism copes with stress will be achieved.